Modification of olefin polymers with unsaturated carboxylic acids produces polymer compositions exhibiting superior adhesion to various substrates, for example, U.S. Pat. Nos. 3,483,276 and 3,987,122. The improvement of adhesion of elastomers to metal when the elastomer is cured using a free radical curing system in the presence of N-maleamic acids or N-maleimide compounds is also known, U.S. Pat. No. 3,502,542. However, to realize the full potential for articles of polymeric material bonded to metal, improved adhesion is needed.